LONDON (AFP) — The US and other key powers said Wednesday they will invite Iran for direct talks on its nuclear activities, as the international charm offensive to bring Tehran in from the cold gathered pace.

EU foreign policy chief Javier Solana will be tasked with extending the invitation to Tehran, said a joint statement from the United States, China, France, Germany, Russia, Britain and the European Union.

The United States' allies welcomed the new direction of US policy towards Iran under President Barack Obama, and its decision to "join in any future meetings with representatives of the Islamic Republic of Iran."

"We strongly urge Iran to take advantage of this opportunity to engage seriously with all of us in a spirit of mutual respect," they said after talks in London.

"To that end, we shall ask (Solana) to extend an invitation to the Iranian government to meet representatives of the E3+3, so that together we may find a diplomatic solution to this critical issue.

"We reaffirm our unity of purpose and collective determination through direct diplomacy to resolve our shared concerns about Iran's nuclear programme, in line with the package proposals for cooperation with Iran."

The six countries -- the five veto-wielding members of the UN Security Council plus Germany and the EU -- issued the statement after a meeting between their political directors.

Under former US president George W. Bush, talks with Iran were led by a trio of European powers -- France, Britain and Germany, the so-called "E3" -- but the United States kept out of direct contacts.

Following Obama's inauguration in January, the six powers said last month they were ready to engage in direct dialogue with Iran, including about its controversial nuclear programme, but had not talked of a formal invitation.

The new statement added: "We recognise once again that Iran has the right to a civilian nuclear programme, but with that comes the responsibility to restore confidence in the exclusively peaceful nature of its nuclear activities.

"We strongly urge Iran to take advantage of this opportunity to engage seriously with all of us in a spirit of mutual respect," they said.

In a direct appeal to the Iranian people at the start of Nowruz, the Iranian New Year, last month, Obama offered to "extend a hand if the other side unclenches its fist" and launch an "honest" engagement with Tehran.

"My administration is now committed to diplomacy that addresses the full range of issues before us, and to pursuing constructive ties among the United States, Iran and the international community," he said.

The two nations have not had diplomatic ties since 1980.

Iran has repeatedly denied that it intends to build a nuclear bomb. But six years of probes by the International Atomic Energy Agency -- the UN nuclear watchdog -- have been unable to resolve the issue.

During that time Europe and the United States have tried to halt the Iranian programme with a mixture of sanctions and the prospect of important trade breaks and improved ties with Washington.

US State Department spokesman Robert Wood told reporters that Washington hoped Iran would accept the invitation for talks, saying they could be "the occasion to seriously engage Iran on how to break the logjam of recent years".

A new poll published Wednesday by CNN television and polling firm Opinion Research found the US public overwhelmingly view Iran as a threat but six in 10 say Washington should hold talks with Tehran in the next few weeks.